axfer: use second argument in command line for transmission direction

axfer: use second argument in command line for transmission direction

In renewed command system, axfer uses first argument for subcommand. In
popular subcommand such as transfer, transmission direction is required.
At present, some options in aplay(1) are used for this purpose however
it's understandable to use second argument for this purpose.

This commit uses second argument as fixed position to indicate
direction for renewed command system.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>